The world’s largest nuclear powers, US, Russia, China, France and the UK have pledged to never enter into a nuclear war, in a rare statement of unity amid rising tensions between the East-West .

Russia is believed to have the world’s biggest stockpile of nuclear warheads, with 6,255, followed closely by the United States at 5,550, according to the Arms Control Association (ACA). China (350), France (290) and the UK (225) round out the top five.

Pakistan (165), India (156), Israel (90) and North Korea (40-50) also have nuclear weapons, according to the ACA, but are not party to the Nonproliferation Treaty.

Although nuclear weapons have only been used twice in warfare—in the US bombings of Hiroshima and Nagasaki in 1945—about 13,400 reportedly remain in our world today and there have been over 2,000 nuclear tests conducted to date..

The top five nuclear countries have now pledged to work together toward “a world without nuclear weapons”

The statement also stressed the importance of preventing conflict between nuclear-weapon states from escalating, describing it as a “foremost responsibility.”

“A nuclear war cannot be won and must never be fought,” said the joint statement, which was issued simultaneously by the United States, Russia, China, the United Kingdom and France.

“As nuclear use would have far-reaching consequences, we also affirm that nuclear weapons — for as long as they continue to exist — should serve defensive purposes, deter aggression, and prevent war.”

The statement comes as a shock as Russia is massing troops along its border with Ukraine, raising alarms in US, UK and the EU of which France is a major power.

While there is increased Chinese military activity around the self-governed island of Taiwan which has spiked tensions between Beijing and Washington and US allies Japan, Australia, South Korea.

The statement released by the five powers, also known as the P5, as permanent members of the United Nations Security Council, called on all states to create a security environment “more conducive to progress on disarmament with the ultimate goal of a world without nuclear weapons with undiminished security for all.”

The five pledged to adhere to the 1970 Nuclear Nonproliferation Treaty (NPT) which obligates them “to pursue negotiations in good faith on effective measures relating to cessation of the nuclear arms race at an early date and to nuclear disarmament.”

Russian Foreign Ministry spokesperson Maria Zakharova said the five-nation statement was initiated by Russia with the intention of it being released in coordination with a review of the Non Proliferation Treatt that started on Tuesday, January 4 in New York .

“Given the importance and self-sufficiency of this joint statement, the nuclear powers decided not to delay its publication,” Zakharova said, according to the official TASS news agency.

Kremlin spokesman Dmitry Peskov told TASS the statement “was negotiated through diplomatic channels” and “comprehensively reflects the positions of the parties and the leaders.”

The director-general of the Chinese Foreign Ministry’s arms control department, Fu Cong, said that China remained committed to a policy of no first use and deterrence.

“Nuclear weapons are the ultimate deterrence. They are not for war fighting. By saying that nuclear war cannot be won and must never be fought shows that this is an understanding shared by all the P5. So it is important that we have this in mind while we talk about the tension,” said Fu when asked about tensions over Taiwan.

“This applies everywhere and it applies with our bad relations with the US … This is something that we hope could reduce tension, and it would help clarify certain misunderstandings,” he added.